One vertex per element, one color per generator, with an edge from x to x·s.
(3,7)(5,8)(9,10)(11,18)(12,20)(13,15)(14,16)(17,22)(19,23)(21,24)(25,26)(27,28)(29,37)(30,34)(31,32)(33,40)(35,38)(36,39) involution — undirected(1,2,4,6)(3,5,7,8)(9,11,15,14)(10,16,13,18)(12,21,22,19)(17,24,20,23)(25,27,31,35)(26,28,32,38)(29,39,40,30)(33,34,37,36)(1,3)(2,5)(4,7)(6,8)(10,13)(16,18)(17,20)(23,24)(26,32)(27,35)(29,40)(34,36) involution — undirected(1,2)(3,5)(4,6)(7,8)(9,12,15,22)(10,17,13,20)(11,19,14,21)(16,23,18,24)(25,28)(26,27)(29,36)(30,33)(31,38)(32,35)(34,40)(37,39)(1,3)(2,5)(4,7)(6,8)(9,13,15,10)(11,16,14,18)(12,20,22,17)(19,23,21,24)(25,29)(26,33)(27,30)(28,36)(31,40)(32,37)(34,38)(35,39)(9,14,15,11)(10,16,13,18)(12,19,22,21)(17,24,20,23)(25,30)(26,34)(27,29)(28,37)(31,39)(32,36)(33,38)(35,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.